Starters for internal combustion engines



March 2, 1965 K. SCHERZINGER v 3,171,284

STARTERS FOR INTERNAL coususnou ENGINES Filed Feb. 14, 1963 Wyn/rap Karl Scherzinger mihael 5. fi'firiker ATTORNEY United States Patent 3,171,284 STARTERS FQR ENTERNAL 0MEUSTKON EQGENES Karl Seherzinger, Stuttgart-Degerloch, Germany, assignor to Robert Bosch Q.m.b.H., Stuttgart, Germany Filed Feb. '14, 1963, Ser. No. 258,480 Claims priority, application Germany, Feb. 17, 1962,

3 65,934 14 Claims. (Cl. 74-7) The present invention relates to engine starters and in particular to starters used for starting internal combustion engines.

In constructions of this type the starter usually includes a pinion which moves into mesh with a gear fixed to or forming part of a fly wheel of the internal combustion engine so that when the starting motor operates the pinion transmits a drive therefrom to the engine in order to start the latter. In constructions of this type the motion of the starting motor is transmitted from its shaft to a hollow shaft which surrounds the motor shaft, this motor shaft having a threaded connection with the hollow shaft so that not only is the rotary motion of the motor shaft transmitted to the hollow shaft but in addition the hollow shaft is axially shifted with respect to the motor shaft and this axial shifting displaces a pinion into and out of mesh with the gear which is connected to the fly-wheel of the internal combustion engine. The threaded portion of the hollow shaft is connected, for example, through an overrunning clutch with a second portion of the hollow shaft which carries the pinion.

It is necessary in constructions of this type to limit the axial shifting of the hollow shaft assembly so that the pinion will remain in proper mesh with the gear which is connected to the fly-wheel, and for this purpose the motor shaft is usually formed with a groove which receives a ball member which shifts with and is located in a bore of the hollow shaft. This ball memher is retained in the bore of the hollow shaft by a ring which surrounds the hollow shaft. In practice it has been found that sometimes the hollow shaft is shifted axially with respect to the motor shaft so fast that the ring does not immediately follow the hollow shaft and thus permits the ball member to ride through and beyond the groove of the motor shaft so that as a result the pinion is not reliably maintained in its operative position where it properly meshes with the gear.

A primary object of the present invention is to avoid this drawback by providing a starter construction which will reliably limit the axial shifting of the pinion so that it cannot move beyond the position where it is in proper mesh with the gear.

Another object of the present invention is to provide a ball-and-groove construction of the type referred to above which, however, can never have the ball move out of the groove, so that in this way the operative position of the pinion with respect to the gear which it drives is guaranteed.

A further object of the present invention is to provide for a starter of the type referred to above a balland-groove construction which will function not only to determine the operative position of the pinion with respect to the gear which it drives but also to determine the rest position of the pinion where it is out of mesh with the gear.

Still another object of the present invention is to pro- Vide a construction of the above type where the structure which determines the position of the pinion with respect to the gear which it drives can have a number of different locations in the assembly, so that in this way 3,171,284 Patented Mar. 2, 1965 ice a flexible construction which is not limited to a particular location of its components can be provided.

Also, the objects of the present invention include a structure of the above type which is exceedingly simple, rugged, and reliable in operation.

With the above objects in view the invention includes, in an engine starter, an elongated hollow shaft means carrying a pinion, and an elongated motor shaft means which extends coaxially into the hollow shaft means. A motion transmitting means is operatively connected to both of these shaft means for transmitting a drive from the motor shaft means to the hollow shaft means and for axially shifting the hollow shaft means with respect to the motor shaft means between a rest position where the pinion is out of mesh with the gear and an operative position where the pinion meshes with this latter gear to drive the same. The hollow shaft means has an inner circumferential surface portion surrounding and directed toward an outer circumferential surface portion of the motor shaft means, and one of these shaft means is formed in its circumferential surface portion with an elongated circumferential groove. A projecting means is operatively connected to and has at all times a predetermined position with respect to the other of these shaft means, and this projecting means projects at all times into the elongated circumferential groove and engages one end of the groove in order to determine the operative position of the hollow shaft means. Since this projecting means remains at all times in the elongated circumferential groove, it can never become displaced therefrom and by engaging one end of the groove when the pinion is in mesh with the gear which it drives the projecting means cooperates reliably with the groove to determine the operative position of the pinion.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a partly sectional, fragmentary, partly diagrammatic illustration of one possible construction of an engine starter according to the present invention;

FIG. 2 is an elongated sectional illustration of the upper portion of an elongated motor shaft and a hollow shaft means which cooperates therewith, the structure of the invention which is included in FIG. 2 being different from the structure of the invention which is included in FIG. 1; and

FIG. 3 is a transverse sectional view taken along line IIIIII of FIG. 2 and showing the entire cross-section of the motor shaft and hollow shaft.

Referring to FIG. 1, there is illustrated therein an elongated motor shaft means 10 which forms the motor shaft of the electric motor of the starter, this electric motor 47 being shown diagrammatically at the upper right portion of FIG. 1. The electric motor 47 includes in addition to the shaft means it an armature 11 fixed to the shaft means 10 so as to rotate the latter when the armature rotates. The elongated motor shaft means 10 has an elongated end portion 12 which has a smooth exterior surface, and the elongated motor shaft means 10 extends coaxia'lly into an elongated hollow shaft means 13, 19, this hollow shaft means including the driven shaft portion 13 which is fixed coaxially with a pinion 14, and in a manner described below the hollow shaft means 13, 19 is movable both circumferentially and axially with respect to the motor shaft means 10. The portion 19 of the hollow shaft means forms a drivingshaft portion thereof, and an overrunning clutch 15 connects the driving shaft portion 19 to the driven shaft portion 13 so as to transmit one direction of rotation of the shaft 19 to the coaxial shaft portion 13 of the hollow shaft means, this construction operating in a manner well-known in the art in such a way that when the pinion 14 and the hollow shaft portion 13 rotate at a speed greater than the motor shaft means It), the drive will not be transmitted back to the motor shaft means 16 so that the motor of the starter cannot be driven at a high speed from the engine after the latter starts. As is well-known the overrunning clutch 15 includes an outer ring 17 formed at its inner periphery with a plurality of substantially wedge-shaped notches respectively receiving the rollers 16 which ride on an exterior circumferential surface portion of the driven shaft portion 13 of the hollow shaft means. A flange 18 which is integral with and projects from the hollow shaft portion 19 is fixed directly to the outer ring 17 of the overrunning clutch 15, and in addition the overrunning clutch serves to prevent axial movement of the shaft portions 13 and 19 with respect to each other while of course permitting the shaft portion 13 to turn relative to the shaft portion 19. Of course, the ring 17 cannot turn with respect to the shaft portion 19.

A motion transmitting means is operatively connected to the motor shaft means it and the hollow shaft means 13, 19 for transmitting a drive from the motor shaft means to the hollow shaft means 13, 19 as well as for axially shifting the hollow shaft means 13, 19 with respect to the motor shaft means 10 between the rest position illustrated in FIG. 1 and an operative position where the pinion 14 meshes with a gear 55 fixed to the fly-wheel of the engine. This motion transmitting means includes an outwardly threaded portion 21 fixed to and projecting from the shaft means 10 and an internally threaded portion 29 of the driven portion 19 of the hollow shaft means, the internally threaded portion 20 meshing with the externally threaded portion 21, and the threads of the portions 20 and 21 have a relatively large pitch. A ring 22 extends around the clutch and has inwardly directed end flange portions respectively overlapping the flange 18, which is fixed to the shaft portion 19, and the thin, flat ring 23 which extends into a groove formed at the exterior of the shaft .portion 13 and which is located directly next to the clutch 15', so that in this way the shaft portions 13 and. 19 together with the overrunning clutch 15 and the pinion 14 form an assembly which is axially shiftable as a unit.

The inner surface of the shaft portion 19 which is provided with the thread 29 forms an inner circumferential surface portion of the hollow shaft means 13, 19 which is directed toward and surrounds an exterior circumferentia'l surface portion of the motor shaft means 1%, and this latter exteriorcircumferential surface portion of the motor shaft means 10 is formed, in the example illusrtrated in FIG. 1, with an elongated circumferential or annular groove 24- coaxial with the motor shaft means iii, and the axial length of the groove 24 corresponds, at least approximately, to the distance a through which the pinion 14 is shifted from its rest position illustrated in FIG. 1 to its operative position meshing properly with the gear 55. In accordance with the present invention a projecting means is operatively connected to and has at all times a predetermined position with respect to the hollow shaft means 13, 19, and this projecting means is located at all times in groove 24 and engages the leftend of the groove 24, as viewed in FIG. 1, so as to determine the operative position of the pinion 14 where the latter has been shifted through the distance a into proper mesh with the gear 55. This projecting mean includes, in the illustrated example, a plurality of ball members 26, one 7 of which is shown in FIG. 1. A part of the hollow shaft portion 19 is formed with a plurality of bores 25 into which the ball'members 26 respectively extend, and these bores 25 are uniformly distributed about the axis of the hollow shaft means 13, 19 and are located in a common plane which is normal to this axis. A ring 27 surrounds and engages the shaft portion 19 and covers the openings 25 so as to retain the ball members 26 in a position ex tending only partly into the bores 25 and at all times projecting into the groove 24.

A spring 23 surrounds the shaft portion 19 and presses at one of its ends against the ring 27 so as to maintain the latter in engagement with a collar 29 which is fixed to the right end of the elongated hollow shaft means 13, 19. The location of the several bores 25 is such that in the rest position'of the hollow shaft means 13, 19 shown in FIG. 1 the several ball members 26 engage the end 3% of the groove 24, so that the end 3t, of the groove 24 cooperates with the ball members 26 for determining the rest position of the hollow shaft means while the opposite end of the groove 24, the left end thereof as viewed in FIG. 1, cooperates with the projecting means 26 for determining the operative position of the hollow shaft means where the pinion 14 is in proper mesh with the gear 55.

During the initial part of the operations performed in order to start an engine with the starter of FIG. 1 the hollow shaft means is shifted to the left, as viewed in FIG. 1, by a two-armed lever 32 supported for turning movement by a stationary pivot pin 31 and having a lower bifurcated portion carrying pins 33 which extend into the space between a pair of rings 34. These rings are respectively situated on opposite sides of the overrunning clutch 15, and while the left ring 34 of FIG. 1 is fixed with respect to the hollow shaft means through suitable spacers and a snap ring, the right ring 34 of FIG. 1 is engaged by the left end of the spring 28 so that,

if necessary, the right ring 34 can shift toward the ring The starter also includes a solenoid switch 35 shown at the upper part of FIG. 1 and including an armature 36 fixedly carrying a coaxial projecting rod 37 which has an enlarged head end, at its left end as viewed in FIG. 1, engaging a washer which in turn engages one end of a spring 33 which is compressed within a hollow member 39 in which the washer is free to move during compression and expansion of the spring 38 which is compressed between this washer and the right end wall of the hollow member 39, as viewed in FIG. 1. The hollow member 39 is provided at its exterior with a pair of circumferential flanges 4 9 between which the upper free end of the lever 32 is located so that shifting of the member 39 will result in turning of the lever 32. As is diagrammatically indicated in FIG. 1, the solenoid switch 35 includes a coil 41 through which the armature 36 extends, and in the electric circuit in which the coil 41 is located there is also a switch 42 capable of being closed and opened at the will of the operator and connected electrically with a source of current 43. In addition, the structure includes a bridging member 4- capable of bridging the stationary contacts 45' and 46 for completing a circuit therebetween, and the armature 36 includes a portion having a flange fixed to one end of the spring the other end of which is fixed to the bridging member 44 so that it is possible for the armature to have some degree of yieldable movement with respect to the bridging member 44. The stationary contact 45 is connected to one pole of the battery 43, the other pole thereof being grounded, and the contact 46 is connected electrically to the starting motor 47.

In order to displace the hollow shaft means 13, 19 together with the pinion 14 carried thereby from the rest position shown in FIG. 1 to the operative position where the pinion 14 meshes properly with the gear 55 which is connected to the fly-wheel of the internal combustion engine, the operator will close the switch 42, in a manner well-known in the art, so as to energize the solenoid switch 35, with the result that the armature 36 thereof will be pulled to the right, as viewed in FIG. 1, in opposition to a spring which urges the armature 36 to the rest position thereof which is illustrated in FIG. 1. The result is that the hollow member 39 also shifts to the right, as viewed in FIG. 1, and thus the lever 02 is turned in a clockwise direction, as viewed in FIG. 1. The dimensions and proportions of the parts are such that before the contacts 45 and 46 are bridged by the bridging member 44, the lever 32 will have acted on the hollow shaft means 13, 19 to an extent sufficient to shift the latter to the left by the distance [2 which places the pinion 14 partly in mesh with the gear 55. Thus, before the contacts 45 and 46 are bridged, which is to say before the starting motor 47 has become energized, the pinion 14 is partly in mesh with the gear 55. The continued advance of the armature 36 to the right, as viewed in FIG. 1, places the bridging member 44 in engagement with the contacts 45 and 4s so that the starting motor starts to operate and the motor shaft means of course starts to turn so that the motion transmitting means will have its portion 21 turning with respect to its portion 20 so that the threaded portion 21 tends to thread itself into the threaded portion 29 with the result that the motion transmitting means shifts the hollow shaft means 13, 19 further to the left, as viewed in FIG. 1, until the projecting means 26 engages the left end of the groove 24, as viewed in FIG. 1, so as to limit the movement of the pinion 14 to the total distance a which thus locates the pinion 14 in its proper meshing engagement with the gear 55. Of course, the motion transmitting means also serves at this time to transmit the rotation of the shaft 10 to the shaft portion 19 which, at this time, through the overrunning clutch 15, drives the shaft portion 13 and the pinion 14 so that the engine is cranked. The cooperation of the ball members 26 with the left end of the slot 24 limits the movement of the hollow shaft means together with the pinion 14, and this feature of the invention prevents the hollow shaft means, the pinion 14, and the overrunning clutch from moving through a distance greater than that required to place the pinion 14 in proper mesh with the gear 55. It will be noted that during the entire shifting movement of the hollow shaft means 13, 19 with respect to the motor shaft means It the ball members 26 remain at all times in the groove 24 and are held therein by .the ring 27 which in effect forms an outer wall portion of the hollow shaft means covering openings formed in an inner wall portion thereof, which is to say the wall portion of the hollow shaft 19 which is surrounded by the ring 27, so that it is not possible for the ball members 26 to have any other location except one where they project into the groove 24, so that a very reliable operation is guaranteed.

It is not absolutely essential that the ball-and-groove construction of FIG. 1 be situated at the location illustrated in FIG. 1, and FIGS. 2 and 3 show another embodiment where, instead of locating the part 21 of the motion transmitting means between the groove 24 and the pinion 14, as shown in FIG. 1, the groove of the ball-and-groove structure is situated between the motion transmitting means and the pinion 14.

Referring to FIG. 2 it will be seen that the hollow shaft means 10 is not provided with a groove 24 and instead has a longer threaded portion meshing with an inner threaded portion of the hollow shaft means. In this case, instead of the groove 24, the shaft means 10 is formed with an elongated circumferential groove 43 situated adjacent the left free end of the shaft 10. The axial length of the groove 48 also corresponds substantially to the distance a through which the pinion 14 moves between its rest and operative positions. It is to be noted that in the case of both grooves 24 and 48, it is the bases of these grooves, which is to say their cylindrical portions which are nearest to the axis of the shaft 10, which have a length corresponding to the distancea through which the pinion 14 moves between its rest and operative positions. In the embodiment of FIG. 2 the pinion 14 is fixed coaxially with a relatively short hollow shaft portion 49 of the hollow shaft means, this portion 49 forming in this case the inner wall portion of the hollow shaft means which is formed with the radial bores 54 passing therethrough and receiving the ball members 51, the bores 50 corresponding of course to the bores 25 and the ball members 51 corresponding of course to the ball members 26. With the embodiment of FIG. 2 the structure is also arranged in such a way that when the hollow shaft means and the pinion 14 are in their rest position the projecting means formed by the ball members 51 engages the end of the slot 48 opposite from the end thereof which is engaged by the projecting means 51 when the hollow shaft means is in its operative position, so that in this case also the ball-and-groove construction serves to determine both of the positions the hollow shaft means; The relatively short portion 49 of the hollow shaft means extends into an elongated portion 52 thereof, and it is this portion 52 which forms the outer wall means surrounding the shaft portion 49 and closing the bores 50 thereof so that the ball members 51 are reliably maintained in the position where they project at all times into the groove 48. As may be seen from FIG. 3, the shaft portion 49 has a splined connection with the shaft portion 52 so that these shaft portions are constrained to rotate together. The left free end of the shaft portion 52 fixedly carries a ring 54 which extends into a groove 53 formed in the exterior of the shaft portion 49, and it will be seen that the right end of the shaft portion 49, as viewed in FIG. 2, engages an inner shoulder of the shaft portion 52 while the inner periphery of the ring 54 engages a shoulder formed by the right end of the groove 53, so that in this way the shaft portions 49 and 52 are also constrained to move axially as a unit.

Except for the above-noted differences, the embodiment of FIG. 2 is identical with that of FIG. 1 and operates in the same way.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of engine starters differing from the types described above.

While the invention has been illustrated and described as embodied in limiting structures for engine starters, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In an engine starter, in combination, elongated hollow shaft means carrying a pinion; elongated motor shaft means extending coaxially into said elongated hollow shaft means; means operatively connected to ,both of said shaft means for transmitting a drive from said motor shaft means to'said hollow shaft means and for axially shifting said hollow shaft means with respect to said motor shaft means between a rest position where said pinion is out of mesh with a gear to be driven thereby and an operative position where said pinion meshes with said gear to transmit a drive thereto, said hollow shaft means having an inner circumferential surface portion directed toward and surrounding an outer circumferential surface portion of said motor shaft means and '7 one of said shaft means being formed'at said circumferential surface portion thereof with an elongated annular groove coaxial with said shaft means; and projecting means operatively connected to and having at all times a predetermined position with respect to the other of said shaft means, said projecting means being located at all times in said groove engaging one end of said groove for determining the operative position of said.

elongated hollow shaft means with respectto said motor shaft means.

2. In an engine starter, in combination, elongated hollow shaft means carrying a pinion; elongated motor shaft means extending coaxially into said hollow shaft means; motion transmitting means operatively connected to both of said shaft means for transmitting a drive from said motor shaft means to said hollow shaft means and for shifting said hollow shaft means with respect to said motor shaft means between a rest position where said pinion is out of mesh with a gear and an operative position where said pinion meshes with said gear to drive the same, said hollow shaft means having an inner circumferential surface portion surrounding and directed toward an outer circumferential surface portion of said motor shaft means, and said motor shaft means being formed at said outer circumferential surface portion thereof with an elongated annular groove coaxial with said shaft means; and projecting means operatively connected to said hollow shaft means and having at all times a predetermined position with respect thereto, said projecting means projecting at all times into said groove and engaging one end thereof for determining the operative position of said hollow shaft means with respect to said motor shaft means.

3. In an engine starter, in combination, elongated hollow shaft means carrying a pinion; elongated motor shaft means extending coaxially to said elongated hollow shaft means; motion transmitting means .operatively connected to both of said shaft means for transmitting a drive from said motor shaft means to said hollow shaft means and for shifting said hollow shaft means with respect to said motor shaft means between a rest position where said pinion is out of mesh with a gear and an o erative position where said pinion meshes with said gear to drive the same, said hollow shaft means having an inner circumferential surface portion surrounding and directed toward an outer circumferential surface portion of said motor shaft means and said motor shaft means being formed at said outer circumferential surface portion thereof with an elongated groove, said motion transmitting means including a motion transmitting member fixed to and extending from said motor shaft means into operative engagement with said hollow shaft means and located between said groove and said pinion; and proecting means operatively connected to and having at all times a predetermined position with respect'to said hollow shaft means and projecting at all times into said groove, said projecting means engaging one end of said groove for determining the operative position of said hollov shaft means.

4. In an engine starter, in combination, elongated hollow shaft means carrying a pinion; elongated motor shaft means extending coaxially into said hollow shaft means; motion transmitting means operatively connected to both of said shaft means for transmitting a drive from said motor shaft means to said hollow shaft means and for axially shifting said hollow shaft means between a rest position where said pinion is out of mesh with a gear and an operative position where said pinion meshes with said gear to drive the same, said motion transmitting means including a motion transmitting member fixed to said motor shaft means and extending therefrom into operative engagement with said hollow shaft means, said motor shaft means being formed between said motion transmitting member and said pinion with an elongated circumferential groove; and projecting'means operatively connected to and having at all times a predetermined position with respect to said hollow shaft means, said projecting means projecting into said groove at all times and engaging one end of said groove for determining the operative position of said hollow shaft means with respect to said motor shaft means.

5. In an engine starter, in combination, elongated hollow shaftmeans carrying a pinion; elongated motor shaft means extending coaxially into said hollow shaft means; motion transmitting means operatively connected to both of said shaft means for transmitting a drive from said motor shaft means to said hollow shaft means and for shifting said hollow shaft means between a rest position where said pinion is out of mesh with a gear and an operative position where said pinion meshes With said gear to drive the same, said motor shaft means being formed with an elongated annular groove coaxial with said shaft means and said elongated hollow shaft means having a Wall portion formed with a radial bore; and a ball member located at all times in said bore and .projecting at all times into said groove of said motor shaft means, said ball member engaging one end of said groove for determining the operative position of said hollow shaft means.

6. An engine starter as set forth in claim 5, wherein said hollow shaft means has a wall portion formed with a plurality of radial bores angularly spaced from each other and wherein a plurality of ball members are respectively located at all times in said bores and projecting at all times into said groove of said motor shaft means, said ball members engaging one end of said groove for determining the operative position of said hollow shaft means.

7. Inan engine starter, in combination, elongated hollow shaft means carrying a pinion; elongated motor shaft means extending coaxially into said elongated hollow shaft means; motion transmitting means operatively connected to both of said shaft means for transmitting a drive from said motor shaft means to said hollow shaft means and for shifting said hollow shaft means between a rest position where said pinion is out of mesh with a gear and an operative position Where said pinion meshes with said gear to drive the same, said hollow shaft means having an inner circumferential surface portion surround ing and directed toward an outer circumferential surface portion of said motor shaft means, and one of said shaft means being formed at said circumferential surface portion thereof with an elongated circumferential groove having a length which is approximately equal to the distance through which said hollow shaft means is shifted between said positions thereof; and projecting means operatively connected to and having at all times a predetermined position with respect to the other of said shaft means, said projecting means extending into said groove and engaging one end thereof for determining the operative position of said hollow shaft means.

8. In an engine starter, in combination, elongated hollow shaft means carrying a pinion; elongated motor shaft means extending coaxially into said hollow shaft means; motion transmitting means operatively connected to both of said shaft means for transmitting a drive from said motor shaft means to said hollow shaft means and for axially shifting said hollow shaft means with respect to said motor shaft means between a rest position where said pinion is out of mesh with a gear and an operative position where said pinion meshes with said gear to drive the same, said motor shaft means being formed with an elongated annular groove coaxial with said shaft means and said hollow shaft means being formed with a radial bore passing through a wall portion of said hollow shaft means; a ball member located in part in said bore of said hollow shaft means and extending at all times into said groove, said ball member engaging one end of said groove for determining the operative position of said hollow shaft means; and a ring carried by and surrounding said hollow shaft means and closing, at least partly, said radial bore thereof at all times, said ring retaining said ball member in a position where it cannot project through said radial bore outwardly beyond said hollow shaft means.

9. In an engine starter, in combination, elongated hollow shaft means carrying a pinion; elongated motor shaft means extending coaxially into said elongated hollow shaft means; motion transmitting means operatively connected to both of said shaft means for transmitting a drive from said motor shaft means to said hollow shaft means and for axially shifting said hollow shaft means with respect to said motor shaft means between a rest position where said pinion is out of mesh with a gear and an operative position where said pinion meshes with said gear to drive the same, said motor shaft means being formed with an elongated annular groove coaxial with said shaft means and said hollow shaft means having an inner wall portion formed with an opening passing therethrough and an outer Wall portion surrounding said inner wall portion and at least substantially closing said opening thereof; and a ball member located in said opening of said inner wall portion of said hollow shaft means and retained in said opening by said outer wall portion thereof, said ball member extending at all times into said groove of said motor shaft means and engaging one end of said groove for determining the operative position of said hollow shaft means.

10. In an engine starter as recited in claim 9, said outer Wall portion of said hollow shaft means being in the form of a ring surrounding said inner Wall portion thereof.

11. In an engine starter, in combination, elongated hollow shaft means carrying a pinion; elongated motor shaft means extending coaxially into said elongated hollow shaft means; motion transmitting means operatively connected to both of said shaft means for transmitting a drive from said motor shaft means to said hollow shaft means and for axially shifting said hollow shaft means with respect to said motor shaft means between a rest position where said pinion is out of mesh with a gear and an operative position where said pinion meshes with said gear to drive the same, said motor shaft means being formed with an elongated annular groove coaxial with said shaft means and said hollow shaft means having an inner Wall portion formed with an opening passing therethrough and an outer wall portion surrounding said inner wall portion and at least substantially closing said opening thereof; a ball member located in said opening of said inner wall portion of said hollow shaft means and retained in said opening by said outer wall portion thereof, said ball member extending at all times into said groove of said motor shaft means and engaging one end of said groove for determining the operative position of said hollow shaft means; and means connecting said inner and outer wall portions of said hollow shaft means to each other for rotation together and preventing axial movement of said inner and outer Wall portions one with respect to the other.

12. In an engine starter, in combination, elongated hollow shaft means carrying a pinion and including an elongated driving portion and an elongated driven portion located next to and extending axially from said driving portion; overrunning clutch means connecting said driving portion of said hollow shaft means to said driven portion thereof for transmitting a drive from said driving to said driven portion of said hollow shaft means and preventing axial movement of said driving and driven portions of said hollow shaft means one with respect to the other; elongated motor shaft means extending coaxially into said hollow shaft means; motion transmitting means operatively connected to said motor shaft means and said driving portion of said hollow shaft means for transmitting a drive from said motor shaft means to said driving portion of said hollow shaft means, said motion transmitting means also shifting said hollow shaft means axially with respect to said motor shaft means between a rest position where said pinion is out of mesh with a gear and an operative position where said pinion meshes with said gear to drive the same, said motor shaft means being formed with an elongated annular groove coaxial with said shaft means; and projecting means operatively connected to and having at all times a predetermined position with respect to one of said portions of said hollow shaft means and projecting at all times into said groove, said projecting means engaging one end of said groove for determining the operative position of said hollow shaft means.

13. In an engine starter as recited in claim 12, said projecting means being operatively connected to said driving portion of said hollow shaft means.

14. In an engine starter as recited in claim 12, said projecting means being operatively connected to said driven portion of said hollow shaft means.

References Cited by the Examiner UNITED STATES PATENTS BROUGHTON G. DURHAM, Primary Examiner. 

1. IN AN ENGINE STARTER, IN COMBINATION, ELONGATED HOLLOW SHAFT MEANS CARRYING A PINION; ELONGATED MOTOR SHAFT MEANS EXTENDING COAXIALLY INTO SAID ELONGATED HOLLOW SHAFT MEANS; MEANS OPERATIVELY CONNECTED TO BOTH OF SAID SHAFT MEANS FOR TRANSMITTING A DRIVE FROM SAID MOTOR SHAFT MEANS TO SAID HOLLOW SHAFT MEANS AND FOR AXIALLY SHIFTING SAID HOLLOW SHAFT MEANS WITH RESPECT TO SAID MOTOR SHAFT MEANS BETWEEN A REST POSITION WHERE SAID PINION IS OUT OF MESH WITH A GEAR TO BE DRIVEN THEREBY AND AN OPERATIVE POSITION WHERE SAID PINION MESHES WITH SAID GEAR TO TRANSMIT A DRIVE THERETO, SAID HOLLOW SHAFT MEANS HAVING AN INNER CIRCUMFERENTIAL SURFACE PORTION DIRECTED TOWARD AND SURROUNDIGN AN OUTER CIRCUMFERENTIAL SURFACE PORTION OF SAID MOTOR SHAFT MEANS AND ONE OF SAID SHAFT MEANS BEING FORMED AT SAID CIRCUMFERENTIAL SURFACE PORTION THEREOF WITH AN ELONGATED ANNULAR GROOVE COAXIAL WITH SAID SHAFT MEANS; AND PROJECTING MEANS OPERATIVELY CONNECTED TO AND HAVING AT ALL TIMES A PREDETERMINED POSITION WITH RESPECT TO THE OTHER OF SAID SHAFT MEANS, SAID PROJECTING MEANS BEING LOCATED AT ALL TIMES IN SAID GROOVE ENGAGING ONE END OF SAID GROOVE FOR DETERMINING THE OPERATIVE POSITION OF SAID ELONGATED HOLLOW SHAFT MEANS WITH RESPECT TO SAID MOTOR SHAFT MEANS. 